1. Technical Field
The disclosure generally relates to gas turbine engines.
2. Description of the Related Art
Air seals are formed between various components of gas turbine engines, such as between rotating turbine blades and the inner surface of a turbine casing. In this regard, some air seals are provided as an abradable air seal that incorporates an abradable material affixed to the inner surface of the casing. The abradable material is contacted and thus abraded by the rotating blade tips of the turbine blades during operation.
Other air seals are provided as wear resistant seals. Wear resistant seals also employ materials affixed to the inner surface of the casing. Such materials, however, are selected for oxidation resistance and/or thermal protection, for example.
Selection of materials for forming such an air seal typically involves a compromise between resistance to wear by erosion, abradability by blade tips, spallation resistance and environment durability. Notably, materials with higher abradability tend to suffer from excess erosion, while less abradable materials tend to be susceptible to spallation.